HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 452

T glTexParameter Sets the wrap parameter for texture coordinate t to GL_CLAMP, GL_REPEAT, GL_CLAMP_TO_BORDER_EXT, or GL_CLAMP_TO_EDGE_EXT. See the discussion under GL_TEXTURE_WRAP_S. Initially, GL_TEXTURE_WRAP_T is set to GL_REPEAT. GL_TEXTURE_WRAP_R_EXT Sets the wrap parameter for texture coordinate r to GL_CLAMP, GL_REPEAT, GL_CLAMP_TO_BORDER_EXT, or GL_CLAMP_TO_EDGE_EXT. See the discussion under GL_TEXTURE_WRAP_S. Initially, GL_TEXTURE_WRAP_R_EXT is set to GL_REPEAT. GL_TEXTURE_BORDER_COLOR Sets a border color. params contains four values that comprise the RGBA color of the texture border. Integer color components are interpreted linearly such that the most positive integer maps to 1.0, and the most negative integer maps to - 1.0. The values are clamped to the range [0, 1] when they are specified. Initially, the border color is (0, 0, 0, 0). GL_TEXTURE_PRIORITY Specifies the texture residence priority of the currently bound texture. Permissible values are in the range [0, 1]. See glPrioritizeTextures and glBindTexture for more information. GL_GENERATE_MIPMAP_EXT Specifies whether MIP levels should be automatically filtered when the base level (level 0) of a texture map is modified with glTexImage1D, glTexImage2D, glTexImage3DEXT, glTexSubImage1D. glTexSubImage2D, glTexSubImage3DEXT, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, or glCopyTexSubImage3DEXT. The default is GL_FALSE (no automatic generation of MIP levels). GL_TEXTURE_COMPARE_EXT Specifies whether the depth texture comparison operator is in effect. param is either GL_TRUE or GL_FALSE. The default is GL_FALSE, meaning that the depth texture comparison operator is not in effect (see GL_TEXTURE_COMPARE_OPERATOR_EXT, below). GL_TEXTURE_COMPARE_OPERATOR_EXT Specifies the comparison operator to be used when the depth texture comparison operator is in effect and the texture format is one of the GL_DEPTH formats. param is one of GL_TEXTURE_LEQUAL_R_EXT or GL_TEXTURE_GEQUAL_R_EXT. When the depth texture comparison operator is enabled, the r coordinate is interpolated over the primitive and compared with the depth value found at the interpolated s and t coordinate location in the texture map. This comparison is either less-than-or-equal-to (GL_TEXTURE_LEQUAL_R_EXT) or greater-than-or-equal-to (GL_TEXTURE_GEQUAL_R_EXT). The result of the comparison is 0.0 if it fails, or 1.0 if it passes. If texture filtering is enabled, this comparison is performed for all of the texels involved in the filtering operation, and the resulting values interpolated (note that only GL_LINEAR and GL_NEAREST minification and magnification filters are supported for depth texture comparison). This result is passed down as the alpha component of the texture color to subsequent texture application; the red, green, and blue components are set to 0.0. The depth comparison operator is typically used to produce shadow effects. 452 Chapter 18